1. Field of the Invention
The subject invention is generally related to cylinder lock and key sets and is specifically directed to a cylinder lock having a retaining tumbler which is operable without the use of a key.
2. Description of the Prior Art
Cylinder lock and key sets are well known. Typically, the cylinder is rotatably mounted in a sleeve, with the sleeve being permanently installed in a component having a controlled element which is moved between latched and unlatched positions in response to rotation of the cylinder in the sleeve. In keyed locks, the cylinder includes a key slot in communication with a plurality of tumblers, wherein insertion of a properly bitted key in the key slot engages the tumblers and removes them from interfering relationship with the sleeve to permit rotation of the cylinder to move it between the latched and unlatched positions. In unkeyed locks or latch systems, the cylinder is freely rotatable in the sleeve to move between the latched and unlatched positions.
Over the years, it has become common practice to retain the cylinder in assembled relationship with the sleeve by use of a retaining tumbler which is typically spring biased to an extended position with its outer tip in interfering relationship with the opening of the sleeve to preclude axial withdrawal of the cylinder relative to the sleeve after assembly. In most cases, a master key was utilized to withdraw the retaining tumbler into noninterfering relationship with the sleeve to facilitate insertion and removal of the cylinder. While this has been an acceptable design, it created difficult clearance problems when a double-bitted or reversible key was used in combination with the cylinder lock. In addition, this arrangement required redesign of the sleeve and cylinder configuration when non-keyed cylinder lock sets were used as, for example, in combination with glove compartment locks for automobiles and the like.
A number of prior art patents illustrate keyed retainer designs such as, by way of example, U.S. Pat. No. 2,444,542 entitled "Locking and Unlocking Mechanism for Cylinder LockS" issued to G. E. Swanson on Jul. 6, 1948; U.S. Pat. No. 2,629,247 entitled "Cylinder Lock" issued to L. E. Deutsch on Feb. 24, 1953; U.S. Pat. No. 4,272,975 entitled "Cylinder Lock With Key Removable Core" issued to G. P. Patriquin on Jun. 16, 1981; U.S. Pat. No. 4,516,415 entitled "Steering Lock for Automobiles" issued to S. Kobayashi et al on May 15, 1985; and U.S. Pat. No. 4,854,140 entitled "Plunger Lock Mechanism" issued to S. F. Goodman on Aug. 8, 1989.
In particular, the Patriquin patent discloses a cylinder retainer that allows insertion and removal of the cylinder from its sleeve when the retainer is retracted. The retainer is a tumbler located in the tumbler position nearest to the cylinder cap. When a standard key is inserted into the cylinder all of the tumblers will retract except for the retaining tumbler. However, the cylinder may be rotated because of a cam surface located on the retaining tumbler which forces the retaining tumbler inwardly, allowing rotation. A master key is used to retract all of the tumblers including the release tumbler in order to withdraw the cylinder from the sleeve.
The Deutsch patent also discloses a cylinder retaining device. A master key is inserted to withdraw all of the locking tumblers and a retaining tumbler which is not activated by a standard key. Once all of the tumblers are withdrawn by use of the master key, the cylinder may be removed.
All of the known locks of the prior art are either designed to operate the retaining tumbler with use of a master key or eliminate the retaining tumbler from the system where a master key is not utilized.